1. Field of the Invention
This invention relates to a battery pack, and more particularly, is applicable to a battery pack which supplies DC power to electric equipment.
2. Description of the Related Art
Today, many battery packs are commercially available, which contain one or more batteries to supply DC power to portable electronic equipment. A wide variety of battery packs, including those which are rechargeable or are not rechargeable and those which have their specific applications, are on the market. Electronic equipment therefore is likely to be loaded with inappropriate battery packs, thus causing the malfunction of the equipment or damage thereto. A mechanism that is intended to prevent an inappropriate battery pack from being accidentally loaded into electronic equipment is incorporated in battery packs. As an example, a battery pack for a videotape recorder with a camera is shown in FIGS. 1 and 2A to 2C. FIGS. 2A, 2B, and 2C are a plan view, a side view, and a bottom view of the battery pack, respectively.
The battery pack 1 comprises a case 4 consisting of an upper case 2 and a lower case 3, which are provided with a fitting mechanism to prevent the loading of an inappropriate battery pack. A groove 2A on top of the upper case 2 is for preventing the battery pack from being inserted into equipment in an incorrect direction. The battery pack is designed so that if the battery pack is by accident inserted into equipment in an opposite direction, a part of the upper case 2 that is not grooved rests against a guide rail in the equipment to prevent the battery pack from being inserted into the equipment.
On the other hand, the lower case 3 is provided with concave portions 4, 5, 6, and 7 along the center line X--X and with a concave portion 8 along a side wall. The concave portions 5 and 8 are detection holes, and the concave portion 6 is a locking hole used to install the battery pack to electronic equipment of external battery installation type. More specially, the concave portion 4 is a spare detection hole and a detection hole indicating that the battery pack 1 contains a lithium ion battery, respectively. The concave portion 8 is a detection hole indicating that the battery pack 1 is rechargeable.
The lower case 3 is also provided at the sides and bottom thereof with grooves 9A, 9B, 10A, and 10B to install the battery pack to electronic equipment of external battery installation type. A marker 13 indicating the state of charge of the battery, which marker is installed on the side of the lower case 3 on which power supply terminals 11 and 12 are provided, allows it to be determined whether the battery pack 1 is fully charged or depleted.
As described above, a conventional battery pack is designed so that it can be determined, by seeing whether or not convex portions fit into corresponding detection holes, whether or not the battery pack is attachable to electronic equipment or a charger.
In these days electronic equipment has been required to perform more and more functions and provide more accurate information. Such information includes the state of charge of the battery and output current amperage.